Qt绘制网格和曲线

绘制网格：

void Widget::drawGrid(QPainter &p, QRect &windRect)
{QRect   rect(windRect.left()+m_margins.left(),windRect.top()+m_margins.top(),windRect.width()-m_margins.left()-m_margins.right(),windRect.height()-m_margins.top()-m_margins.bottom());if (!rect.isValid())return;QPen    penDot(Qt::DotLine);penDot.setColor(Qt::gray);QPen    penSolid(Qt::SolidLine);penSolid.setColor(Qt::black);
//    pen.setColor(this->palette().light().color());p.setPen(penSolid);p.drawRect(rect.adjusted(0,0,-1,-1));int     Xpos;qreal   Xvalue;QString xlab;QFontMetrics    textSize(this->font());QRect   textRect;for(int i=0;i<=m_XTicks;i++){Xpos=rect.left()+i*m_xRatio; //Xvalue=m_xmin+i*m_xspan/m_XTicks;//p.setPen(penDot);p.drawLine(Xpos,rect.top(),Xpos,rect.bottom());p.setPen(penSolid);p.drawLine(Xpos,rect.bottom(),Xpos,rect.bottom()+5);xlab=QString::asprintf("%.1f",Xvalue);textRect=textSize.boundingRect(xlab);//得到字符串的rectp.drawText(Xpos-textRect.width()/2,rect.bottom()+5+textRect.height(),xlab);}xlab="time(sec)";textRect=textSize.boundingRect(xlab);//得到字符串的rectp.drawText(rect.left()+(rect.width()-textRect.width())/2,windRect.bottom()-textRect.height()/2,xlab);xlab="曲线绘图";textRect=textSize.boundingRect(xlab);//得到字符串的rectp.drawText(rect.left()+(rect.width()-textRect.width())/2,(m_margins.top()-textRect.height())/2+textRect.height(),xlab);int     Ypos;qreal   Yvalue;QString ylab;for(int i=0;i<=m_YTicks;i++){Ypos=rect.bottom()-i*m_yRatio; //Yvalue=m_ymin+i*m_yspan/m_YTicks;//p.setPen(penDot);p.drawLine(rect.left(),Ypos,rect.right(),Ypos);p.setPen(penSolid);p.drawLine(rect.left()-5,Ypos,rect.left(),Ypos);ylab=QString::asprintf("%.1f",Yvalue);textRect=textSize.boundingRect(ylab);//得到字符串的rectp.drawText(rect.left()-10-textRect.width(),Ypos+textRect.height()/2,ylab);}ylab="函数值";textRect=textSize.boundingRect(ylab);//得到字符串的rectp.save();p.translate(0,windRect.height()/2); //平移到左侧中心p.rotate(-90);//逆时针旋转90度，变成正北为X轴，正东为Y轴p.drawText(-textRect.width()/2,(m_margins.left()-textRect.height())/2,ylab);p.restore();
}

绘制曲线：

void Widget::drawCurve(QPainter &p, QRect &windRect)
{QPolygon    curve(m_points.count());for(int i=0;i<m_points.count();i++)curve[i]=m_points[i];QPen    penSolid(Qt::SolidLine);penSolid.setColor(Qt::blue);penSolid.setWidth(2);p.setPen(penSolid);p.drawPolyline(curve);
}